This invention relates to the reproduction of sound film in a motion picture projector which can be operated in different modes of operation, corresponding to different types of film.
Motion picture films with sound track are made in accordance with different standards concerning the number of pictures per unit of time (16 and 24 pictures per second). Also, the type of sound recording (magnetical or optical sound tracks) and the picture size (for example, regular 8 mm and super 8 mm) is different for different types of sound film. Accordingly, universal projectors are available in the trade which can be adapted or adjusted to the different operating conditions so that all of the different types of motion picture films can be projected with such a projector. If, however, the necessary changes have not been made, the projector may break down, possibly, damage the film.